Thermo-acoustic devices are used for conversion of acoustic energy to thermal energy and vice versa. Such a thermo-acoustic device is for example known from U.S. Pat. No. 5,647,216.
The thermo-acoustic device is configured to use a tube or vessel as resonator cavity in which a thermodynamic section is placed. The thermodynamic section comprises an acoustic network. Hart of the network is the thermo-acoustic core which comprises a regenerator and two heat exchangers. The heat exchangers are located at the outer ends of the regenerator and are each configured to exchange heat between a respective external fluid flow and the regenerator. An acoustic driver is situated in the vessel at some distance from the regenerator.
The acoustic power delivered by the acoustic driver to the heat pump in the form of an acoustic wave generates a temperature difference across the regenerator which results in cooling of the fluid flow in one heat exchanger at one end and heating of the fluid flow in the other heat exchanger at the other end. In this manner, the thermo-acoustic device acts as a thermo-acoustic heat pump (TAHP) for pumping heat from low to higher temperature.
Designs of TAHPs are presently restricted to relatively low thermal power applications due to the lack of a suitable driver with a sufficiently high acoustic output power. Disadvantageously, many industrial applications require large amount of process heat which cannot be provided with present TAHP devices.
From U.S. Pat. No. 5,647,216 a thermo-acoustic device is known which acts as a thermo-acoustic refrigerator including a half-wave length resonator, first and second drivers located in housings at first and second ends of said resonator, two pusher cones, a plurality of heat exchangers, a first and second stack, utilizing a compressible gas mixture capable of being tuned to the driver resonance frequency. The pusher cones are driven by voice coils (loudspeakers) and act as coupled acoustic sources that in a 180 degree relative phase shift, generate acoustic waves in the resonator. The output power of such a TAHP is limited by the intensity of the acoustic field generated by the voice coils. The electro-acoustic efficiency of loudspeakers is limited, the construction is not robust enough to produce high acoustic pressure, and the loudspeakers can not be scaled up to high power (for example in the MW range).
JP 2008051408 discloses a pulse tube refrigerator includes: a first refrigerating part including a first coldness storage device, a first pulse tube having a first high temperature end and a first low temperature end, a first passage control means and a first buffer tank, which are sequentially connected to a vibration generator; a second refrigerating part including a first coldness storage device, a second coldness storage device, a second pulse tube having a second high temperature end and a second low temperature end, a second passage control means and a second buffer tank, which are sequentially connected to a high pressure passage and a low pressure passage of the vibration generator; a first passage connecting the first coldness storage device and the vibration generator; a second passage connecting the first passage control means and the first pulse tube; and a third passage connecting the second passage control means and the second pulse tube, wherein the pulse tube refrigerator further includes a by-pass passage connecting the respective passages and a passage, a cylinder provided in the by-pass passage, and a displacer provided to reciprocate in the axial length direction of the cylinder.
DE 4220840 discloses a pulse tube refrigerator system that comprises a compressor volume for compressing an working fluid, a radiator coupled to the compressor volume and arranged for radiating heat, and a regenerator coupled with the radiator.
EP 2781856 relates to a two functional thermal driving traveling-wave thermo-acoustic refrigeration system and discloses a heat-actuated double-acting traveling-wave thermo-acoustic refrigeration system, comprising at least three elementary units, wherein each elementary unit comprises a thermo-acoustic engine, a thermo-acoustic refrigerator, and a resonance device; the thermo-acoustic engine and the thermo-acoustic refrigerator comprise a main heat exchanger, a heat regenerator, a non-normal-temperature heat exchanger, a thermal buffer tube, and an auxiliary heat exchange in sequence; the resonance device comprises a sealed housing in which it is equipped with a moving part being in a reciprocating motion, wherein the moving part separates the housing into at least two chambers; the main heat exchanger and auxiliary heat exchanger of each thermo-acoustic engine and thermo-acoustic refrigerator respectively connects to chambers of different housing, forming a dual-loop structure of gas medium flow. In heating the non-normal-temperature heat exchanger of the thermo-acoustic engine to produce acoustic power, thermo-acoustic energy conversion is induced inside the thermo-acoustic engine and the thermo-acoustic refrigerator. It is an object of the invention to overcome one or more of the disadvantages of the prior art.